The CEAP classification has been used as the reporting standard of chronic venous disease (CVD) since 1995 and was revised in 2004. The following are included in the CEAP classification revised in 2004: refinement of the definitions used in describing CVD, the division of class C4 into two subgroups, i.e., C4a (pigmentation or eczema) and C4b (lipodermatosclerosis or atrophie blanche), the addition of the descriptor “n” (no venous abnormality identified), the incorporation of the date of classification and level of clinical investigation, and the description of “basic CEAP” introduced as a simpler alternative to the advanced CEAP classification (1). However, as the scientific knowledge regarding CVD increased, the necessity to update the CEAP classification arose to reflect current knowledge of CVD. In May 2017, the American Venous Forum created a CEAP Task Force to critically analyze and suggest necessary revisions in the current version of the CEAP classification. The aim of the CEAP classification updated in 2020 is to ensure the reproducibility of clinical findings between physicians, enable a comparison between old and new versions of the CEAP classification, incorporate new evidence-based knowledge into the classification, and provide a balance between simple practical use and highly specific and detailed descriptions of patients with CVD (2).

This review aims to elucidate the updated contents and the background of the 2020 update of the CEAP classifi-cation system.

1) Revision of the “C” component of the CEAP

The clinical classification (C) is the most widely used component of CEAP. Although the C classification is arranged such that more severe manifestations of venous disease are assigned a higher class, the clinical classification was not a quantitative severity scale or scoring system and is not designed to reflect changes over time (3). The clinical classification in CEAP is a descriptive instrument to measure cross-sectional differences between individuals at a single point in time. Etiology, location of incompetent segments, and pathophysiology are described using E, A, and P classifications. Therefore, it is a misconstruction to use the clinical classification in CEAP as the presenting clinical severity over time.

The clinical definitions of each classification have been preserved since the last revision in 2004. As with the 2004 revision, basic CEAP for use in clinical practice should report the single highest C classification in a limb, and advanced (full) CEAP for the researcher and for standardized reporting in scientific journals should report all C classes present in the limb. Each clinical class should be further characterized by a subscript indicating the presence or absence of symptoms (symptomatic vs. asymptomatic) (3).

(1) Addition of the modifier “r” to the C2 and C6 recurrent disease

Recurrence of varicose veins (C2) and venous ulcers (C6) after intervention to correct reflux is common. In 1998, an international consensus group met in Paris and developed a classification for patients with recurrent varices after surgery (REVAS) to be used in conjunction with the CEAP classification. The clinical definition of REVAS is true recurrence, residual refluxing veins, and varicose veins caused by the progression of the disease. When the recurrence occurred on the same site of a previous operation, the causes could include tactical failure, technical failure, neovascularization, and disease progression (4,5). As the pathophysiology of the recurrent venous disease is different from that of primary venous disease, the recurrent disease may have a distinct natural history and may require different strategies for treatment in comparison with primary varicose veins. The tendency of varicose veins and venous ulcers to recur is reflected in the 2020 update of the CEAP classifi-cation, with the addition of the modifier “r” to the C2 and C6 clinical class. Although the clinical definition of recurrence is identical to that of REVAS, the previous treatments are not limited to the surgical treatments (3).

(2) Addition of corona phlebectatica to the C4 class as a separate subclass C4c

Corona phlebectatica was first described in 1960 by Van der Molen (6-8) as a consequence of the venous stasis of the foot. The definition of corona phlebectatica was refined at the revision in 2004 as a fan-shaped pattern of numerous small intradermal veins on the medial or lateral aspects of ankle and foot. Synonyms include malleolar flare and ankle flare (1).

Corona phlebectatica included three elements:

• Telangiectasias, which are dilated intradermal venules, ramifications of “birch twigs” located at the medial or/and lateral aspects of the foot, nest to the malleolar areas. These lesions can be distinguished as blue or red.

• Venous cups extend to the plantar arch as 6∼8 blue cups. These elements occur due to the dilatation of the triangular-shaped venous convergence coming from the plantar arch.

• Stasis spots are made up of sub-epidermal capillaries, nummular, purple-colored areas.

The diagnosis of corona phlebectatica is determined by the presence of blue telangiectasias below the malleolar areas and/or stasis spots (9). The association of blue telangiectasias and stasis spots has the best specificity, and the blue telangiectasias is the most sensible item (9). To complement the diagnostic reproducibility, UIP proposed diagnostic criteria and grades of severity (10) (Table 1).

Table 1 . Proposed criteria for the grading of extension.

Grade 0	<5 telangiectases=C1 (no corona)
Grade I (incipient corona)	<half length of the foot
Grade II (definite corona)	≥half length of the foot

Grade I: Incipient corona (or corona grade 1): more than five clusters of bluish intradermal veins in the sub-malleolar area.

Grade II: Definite corona (or corona grade 2): tortuous bluish intradermal veins with a diameter less than 3 mm in the sub-malleolar area, extended over the half length of the foot or more (Fig. 1).

Figure 1. Corona phlebectatica.

The deciding characteristics to differentiate corona phlebectatica from telangiectasia of the ankle classified C1 are as follows (9):

• More than five non-confluent intradermal veins.

• The presence of stasis spots (clusters of dilated papillary capillaries).

• An extension equal or superior to half the length of the foot (criterion of grade 2 corona phlebectatica).

• Tiny areas of perivenous pigmentation.

Many phlebologists consider corona phlebectatica to be an early sign of advanced venous disease and to warrant inclusion in more advanced C categories. In the Venous Clinical Severity Score (VCSS), revised in 2010, corona phlebectatica was included in the VCSS scoring system but restricted to a score of “1” (mild) in the varicose veins score. Clinical data from a series of 872 patients evaluated by 49 angiologists from nine European countries demonstrated a statistical association between corona phlebectatica and clinical severity classes (11). In the hemodynamic correlation, the relative risk of finding incompetent leg or calf perforators by duplex ultrasound is 4.4 times greater in patients with corona phlebectatica (12). Furthermore, in a case control study, Lindsay Robertson reported that patients with corona phlebectatica have been demonstrated to be 5.3 times more likely to develop an ulcer, and the risk is similar to that of eczema (C4a) and lipodermatosclerosis (C4b) (13). These results suggest that corona phlebectatica should not be considered similar to telangiectasias and reticular veins in other locations. Therefore, accounting for the association of corona phlebectatica with more advanced venous disease, corona phlebectatica was placed in the C4 class as a separate subclass C4c in the 2020 update of the CEAP classification.

The clinical class in the 2020 update of the CEAP classification is presented in Table 2.

Table 2 . Clinical class in the 2020 update of the CEAP classification.

C class	Description
C0	No visible or palpable signs of venous disease
C1	Telangiectasias or reticular veins
C2	Varicose veins
C2r	Recurrent varicose veins
C3	Edema
C4	Changes in skin and subcutaneous tissue secondary to chronic venous disease
C4a	Pigmentation or eczema
C4b	Lipodermatosclerosis or atrophie blanche
C4c	Corona phlebectatica
C5	Healed ulcer
C6	Active venous ulcer
C6r	Recurrent active venous ulcer

2) Revisions to the etiologic classification (E)

In the 2004 revision of the CEAP classification, there is no clear-cut description of the two different etiologies for secondary venous disease. Although clinical venous signs and symptoms are similar between intravenous and extravenous causes of venous disease, treatment options addressing different components are necessary. In the 2020 update of the CEAP classification, secondary etiologies of chronic venous disease are subcategorized into two subclasses (Esi and Ese).

Intravenous secondary causes of venous disease (ESi) are defined as any intravenous condition causing venous wall and/or valve damage, resulting from conditions such as deep vein thrombosis, traumatic arteriovenous fistulas, primary intravenous sarcoma, or other luminal changes inside the vein.

Extravenous secondary causes of venous disease (Ese) are defined as the condition affecting venous hemodynamics, either systemically (e.g., obesity and congestive heart failure) or locally by extrinsic compression (e.g., extravenous tumor, crossing iliac artery, and local perivenous fibrosis) with no venous wall or valve damage. Muscle pump dysfunction due to motor disorders (paraplegia, arthritis, chronic immobility, and frozen ankle) is also an extravenous secondary cause of venous disease since muscle pump dysfunction causes hemodynamic changes in the venous system of the lower extremity with no venous wall or valve damage (3). In a retrospective study analyzing abdominal computed tomography scans conducted in 50 consecutive patients evaluated in the emergency department because of abdominal pain, Kibbe et al. reported that the left iliac vein was compressed more than 25% by the right iliac artery in 66% of enrolled patients and concluded that compression of the left iliac vein may represent a normal anatomic pattern (14). However, interruption of a major venous pathway cannot be considered a normal variant, rather only clinically asymptomatic. Raju et al. reported that nonthrombotic iliac vein lesions (NIVL) such as compression of the left iliac vein by the crossing of the right iliac artery are considered a permissive condition predisposing the development of chronic venous disease (15). Permissive conditions are pathologic conditions that may remain silent until an additional pathology is superimposed. Concomitant venous reflux or the superimposed pathology could render a limb with NIVL symptomatic. Hemodynamic abnormalities may be present even in the absence of symptoms in patients with NIVL. In a study analyzing the late clinical results of superficial femoral vein ligation performed in 35 limbs, 86% of patients showed good tolerance without symptoms over long-term (16). Intravascular ultrasound (IVUS) is recommended as a diagnostic and procedural tool in iliac-caval stenting (17). When NIVL is combined with venous reflux, treatment of the permissive condition first is recommended because treatment of the permissive condition alone may provide symptom relief. Raju et al. reported that 75% of limbs with NIVL and concurrent venous reflux experienced a good outcome with stent placement alone, even when the reflux was uncorrected (15).

The etiologic classification in the 2020 update of the CEAP classification is presented in Table 3.

Table 3 . Etiologic classification in the 2020 update of the CEAP classification.

E class	Description
Ep	Primary
Es	Secondary
Esi	Secondary – intravenous
Ese	Secondary – extravenous
Ec	Congenital
En	No cause identified

3) Revisions to the anatomic classification (A)

In the 2020 update of the CEAP classification, standard abbreviations of anatomical terms are used for the classifi-cation of vein segments instead of numbering since using numbers to denote venous segments is believed to be too difficult to effectively use, and the use of the abbreviations should increase the specificity and reproducibility of CEAP.

A summary of the anatomic classification (A) in the 2020 revision of CEAP is presented in Table 4.

Table 4 . Summary of the anatomic classification (A) in the 2020 update of the CEAP classification.

A class	Description
As	Superficial
	Old	New	Description
	1.	Tel	Telangiectasia
	1.	Ret	Reticular veins
	2.	GSVa	Great saphenous vein above knee
	3.	GSVb	Great saphenous vein below knee
	4.	SSV	Small saphenous vein
		AASV	Anterior accessory saphenous vein
	5.	NSV	Nonsaphenous vein
Ad	Deep
	Old	New	Description
	6.	IVC	Inferior vena cava
	7.	CIV	Common iliac vein
	8.	IIV	Internal iliac vein
	9.	EIV	External iliac vein
	10.	PELV	Pelvic veins
	11.	CFV	Common femoral vein
	12.	DFV	Deep femoral vein
	13.	FV	Femoral vein
	14.	POPV	Popliteal vein
	15.	TIBV	Crural (tibial) vein
	15.	PRV	Peroneal vein
	15.	ATV	Anterior tibial vein
	15.	PTV	Posterior tibial vein
	16.	MUSV	Muscular veins
	16.	GAV	Gastrocnemius vein
	16.	SOV	Soleal vein
Ap	Perforator
	Old	New	Description
	17.	TPV	Thigh perforator vein
	18.	CPV	Calf perforator vein
An	No venous anatomic location identified

4) Revisions to the pathophysiologic classification (P)

The P component of CEAP remains unchanged in the 2020 update of the CEAP classification (Table 5).

Table 5 . Pathophysiologic classification (P) in the 2020 update of the CEAP classification.

P class	Description
Pr	Reflux
Po	Obstruction
Pr,o	Reflux and obstruction
Pn	No pathophysiology identified

In the 2020 update of the CEAP classification system, the clinical classification had the most dramatic revisions. Researchers should understand the definition of the recurrence of varicose veins and take into consideration that corona phlebectatica, which was classified as C1 (telangiectasia) in the CEAP revised in 2004, is newly classified as C4c in the 2020 update of the CEAP classification. The diagnosis of corona phlebectatica is determined by the presence of blue telangiectasias below the malleolar areas extending equal or superior to half the length of the foot and can be reinforced by stasis spot or perivenous pigmentation.

None.